A strange yet infuriatingly catchy video is quickly becoming a viral hit in Sweden and around the rest of the world.

However it is usually on the second or third viewing that non-Swedish viewers realise they are listening to a song which teaches children about penises and vaginas.

Some of the lyrics translate as: ‘Here comes the penis at full pace’, and: ‘the vagina is cool, you better believe it, even on an old lady. It just sits there so elegantly’. (They reportedly sound much less weird in Swedish).

The minute-long clip, called Snoppen och Snippan, was made for Swedish children’s programme Bacillakuten, and features the child-friendly words for penis and vagina: ‘snipp’ and ‘snopp’.

Bacillakuten uploaded the clip to their Facebook page where is has been watched more than 500,000 times.

However opinion of the tune has been varied, with some commentators getting so aggressive that Bacillakuten have had to step in to remind users that many children visit their Facebook page, in a bid to tone down the foul language being used.

One user wrote: ‘What a great song about the most natural thing there is. I think it was my daughter, however, who was bopping along the most.’

Another was less appreciative, and commented: ‘How a clip like this got the green light is the most bizarre thing of the year – and the year is only eight days old.’